Optical networks, such as Passive optical networks (PONs) and Ethernet passive optical networks (EPON), are commonly used in the present world for providing a variety of services, like telephony, cable television and internet, simultaneously to subscribers. A typical PON consists of an Optical line termination (OLT) at a service provider's office and a number of Optical Network Units (ONTs) near end users. The ONTs de-multiplex the optical signal received from the service provider into its various components, viz. telephony, cable television and data. The optical signal is transmitted to the ONTs through a fibre optic cable while the demultiplexed component signals from the ONTs are transmitted to the subscriber's home devices by using various output cables, such as CAT 6, RJ-11 and the like, corresponding to the type of component signals.
In this manner, PON provides for an efficient and quick mechanism of giving variety of services to subscribers. Accordingly, there is a constant need for improving the existing PONs to take such means of communications to higher and much faster level.
More specifically, it has been noted that over the years, no media other than the Optical Fibre Cable (OFC) has been successfully used for increasing the resiliency of optical networks. Network resilience is an important requirement so as to provide and maintain an acceptable level of service when faults occur in the network. Thus, network resilience means the capability of the communication network to be fault tolerant. Therefore, there is a need to increase the resilience of the optical networks, especially PON networks.
Generally, in conventional PONs, network resiliency at the time of breakdown of the backbone optical path is provided by backup optical fiber cables. However, such technique is not very reliable since the backup optical fiber cables may also break down thereby resulting in no resiliency at all. Also, at times it is difficult to lay optical fiber cables and thus it is difficult to ensure network resiliency.
A recent advancement in the field of communication is the improvement in practical applications of Free Space Optics (FSO) communication. It will be apparent to a person skilled in the art that FSO communication is a line-of-sight communication, which uses invisible beams of light to provide optical bandwidth connections. FSO communication has been tested to be capable of delivering multiple (1.25/2.5/10)Gigabytes per second (Gbps) of data, voice, and video communications simultaneously through the most available medium, i.e., air. The FSO communication, therefore, enables fibre optic connectivity without actually requiring physical fibre optic cables. Further, the communication is fast—at the speed of light, and apart from few practical issues, is easy to deploy and use. Therefore, there is an imperative need of integrating FSO based communication in the PONs, thereby providing faster, reliable and higher throughput communication solutions.